Portable electronic devices for example mobile phones play an important role in many emergency situations. A simple phone call or a short message at an earliest time could save lives and change situations. Many of the portable electronic devices are power supplied by a rechargeable battery. The availability of the battery power is a crucial point for employing the portable electronic devices. Users always feel frustrated when a device is not available because of an empty battery. Users may even feel as if their chargeable devices with empty batteries are next to worthless during mains power blackout.
Currently there are many different existing backup power solutions and devices which can be used to provide electricity during mains power blackout. For example, diesel fueled aggregate units commonly called uninterruptible power supply (UPS). Such emergency power unit is driven by diesel fuel and starts up within the first seconds of a blackout. This solution is expensive and also heavily depends on the amount of fuel available in the aggregate unit. Another available solution is to use special battery units designed to recharge the chargeable battery without an actual charger. Users can plug the special battery units into the charge port of the device, and then from there the users will be able to give the device for example an hour extra running time. Such kind of special battery units are normally disposable and pricey which are not commonly used by the consumers. Users can also bring spare rechargeable battery units which can replace or recharge the original battery of the device. In this case the users consume the energy from the backup battery for all kinds of functions including emergency use when it is needed. The users need to remember of recharging the battery in regular basis because battery self-discharge and unit leakage current will slowly discharge the battery. As a battery ages, the users also need to keep track the status of battery by themselves and make sure the backup battery is ready to use when it is needed.